Method of peritoneal dialysis involving ultraviolet radiation of dialysis apparatus

ABSTRACT

The incidence of peritonitis is reduced in continuous ambulatory peritoneal dialysis by irradiating the peritoneum access tube connection with ultraviolet (UV) radiation so as to have an antimicrobial effect on the fluid flow path defined thereby prior to draining and infusion of dialysis fluid therethrough. The apparatus for effecting UV irradiation of the dialysis fluid flow path includes a housing for enclosing the tube connection. Contained inside the housing is a source of UV radiation for irradiating the tube connection. A UV radiation source control circuit establishes the irradiation cycle based on time of exposure. A UV radiation intensity measuring cirucit may also be used to maintain UV source output until a predetermined cumulative UV exposure has been attained.

This is a divisional of application Ser. No. 270,800, filed June 5,1981, now U.S. Pat. No. 4,475,900.

BACKGROUND OF THE INVENTION

The present invention relates generally to fluid infusion methods forperforming peritoneal dialysis on a patient, especially continuousambulatory peritoneal dialysis (CAPD). The present invention furtherrelates to methods and apparatus for preventing peritonitis in a patientundergoing peritoneal dialysis treatment.

In the treatment of patients suffering acute or a chronic renalinsufficiency due to loss of normal kidney function, dialysis therapy isemployed. The two general categories of dialysis therapy arehemodialysis and peritoneal dialysis. In hemodialysis, a patient's bloodis cleansed by passage through an artificial kidney. In peritonealdialysis, dialysis fluid is infused into the patient's peritonealcavity, which is lined by the peritoneal membrane, and metabolites areremoved from the patient's blood by diffusion across the peritonealmembrane; water is also removed because of the osmotic effect of thedialysis fluid.

Within the general category of peritoneal dialysis, modern applicationhas resulted in several peritoneal dialysis techniques. Foremost amongthe peritoneal dialysis techniques are standard intermittent peritonealdialysis (IPD) and continuous ambulatory peritoneal dialysis (CAPD).

The usual clinical procedure for a patient beginning peritonealdialysis, after the surgical implantation of a catheter into theperitoneal cavity, involves infusion of dialysis fluid into theperitoneal cavity of a patient, where it is allowed to equilibrate for aperiod of time and then drain from the peritoneal cavity.

IPD is performed intermittently, with intensive treatments beingconducted two to four times per week. In each treatment, dialysis fluidis rapidly infused and allowed to equilibrate for up to 90 minutes,after which it is removed.

IPD is performed using clamps, connection tubing, and exchangecontainers, the manipulation of which entails careful and time-consumingattention by a competent nursing staff. The frequent handling of freshand waste dialysis fluid bottles and the connection apparatus presents asubstantial risk of infection to the peritoneum. Because of the highrisk of infection, and because trained personnel need to be available toperform IPD, IPD has not gained widespread usage. In an attempt toreduce the risk of infection and minimize nursing time, automaticdialysis fluid cycling equipment for automating the dialysis procedurehas been adopted in many instances.

Continuous ambulatory peritoneal dialysis (CAPD), which is a recentmedical discovery, differs from IPD. In CAPD, multiple dialysis fluidexchanges are performed daily with a significantly longer intervalbetween exchanges being employed when compared with IPD, such that asubstantially constant presence of dialysis fluid is maintained within apatient at all times. A description of the continuous ambulatoryperitoneal dialysis technique may be found in Popovich, et al. U.S. Pat.No. 4,239,041, issued Dec. 16, 1980 and entitled "METHOD FOR CONTINUOUSAMBULATORY PERITONEAL DIALYSIS."

To perform CAPD, an in-dwelling catheter capable of having a peritoneumaccess tube connected thereto is implanted in the peritoneal cavity. Adialysis solution bag containing about two liters of dialysis solutionis attached to the free end of the tube, and the fluid is infused intothe peritoneal cavity. The dialysis solution bag is preferably plasticand flexible. Dianeal® dialysis solution in plastic, flexible bags ismanufactured and sold by Travenol Laboratories, Inc., Deerfield, Ill.and may be used in practicing CAPD.

After infusion, the access tube is clamped off and the patient folds upthe empty bag, which is then carried by the patient while dialysis takesplace. Alternatively, the empty bag can be disconnected from the accesstube and a cap placed on the external coupling connector at the end ofthe access tube; when the patient thus "caps off", the patient may useglass or plastic bottles of dialysis solution as an alternative to thepreferred plastic bags since a primary benefit of the plastic bags isthat they can be rolled for carrying by the patient while dialysis takesplace.

After the period of dialysis fluid residence (dwell), the patient, ifwearing the bag, unwraps the empty plastic bag, lowers it to the floor,releases the clamp and lets the waste-laden dialysis fluid drain out ofthe peritoneal cavity. Next a new bag of fluid is attached, and freshfluid is infused into the peritoneal cavity. If the patient is notwearing the empty bag during dwell, the cap on the end of the supplytube is removed and a drainage bag or other suitable container isattached thereto. After draining of fluid from the peritoneal cavity, anew bag of fresh fluid is attached and the fresh fluid is infused.

Continuous ambulatory peritoneal dialysis permits a patient to carry outhis normal daily activities while dialysis is taking place. Also,because CAPD is much simpler than IPD, a patient can readily administerthe treatment himself at home.

For many years, peritonitis has been a complication of long-termperitoneal dialysis for end-stage kidney disease. With CAPD, the risk ofperitonitis is reduced, but improved infusion methods and apparatus areneeded to permit CAPD to reach its full potential. The present inventionseeks to reduce the incidence of infection in peritoneal dialysisprocedures in general and in continuous ambulatory peritoneal dialysisin particular.

SUMMARY OF THE INVENTION

In accordance with the present invention, the risk of infection to apatient undergoing peritoneal dialysis treatment is substantiallyreduced by irradiating with UV radiation potentially contaminableportions of the dialysis fluid exchange apparatus to thereby have anantimicrobial effect on the same.

The present invention is particularly advantageous for continuousambulatory peritoneal dialysis (CAPD), since a patient undergoing CAPDtypically administers the treatment to himself at home. However, thepresent invention is also effective to reduce like infection hazardsassociated with conventional intermittent peritoneal dialysis, whethercarried out using a gravity flow set or an automatic dialysis fluidcycling machine.

A method of peritoneal dialysis therapy for a patient in accordance withthe present invention involves the patient connecting a source ofdialysis fluid to the peritoneum access tube and irradiating theconnection between the access tube and fluid source with ultravioletradiation prior to infusing dialysis fluid into the peritoneal cavity.The method of the present invention may be utilized when the source ofdialysis fluid is a container having an outlet tube for connection tothe peritoneum access tube; in this situation, the potentialcontamination zone adjacent the connection of the access tube andcontainer outlet tube is irradiated with ultraviolet radiation. Dialysisfluid is then infused into the patient through the access tube.

If desired, irradiation may continue during infusion of fresh dialysisfluid.

Typically, in CAPD, the container is a plastic bag which remainsattached to the access tube after infusion of fresh dialysis fluid, andis rolled-up and carried by the patient while the fluid is in theperitoneal cavity for a residence time period (dwell). After theresidence period, the fluid is drained into the empty bag, and the bagis then disconnected. The aforementioned steps of connecting a new bag,irradiating the connection, and infusing fresh fluid are then repeated.

Sometimes, however, it might be desired to disconnect the container fromthe access tube after infusion. In that case, prior to draining thespent fluid, an empty container is connected to the access tube, and toavoid possible infection, preferably the connection between the emptycontainer and the access tube is irradiated with ultraviolet radiation.Then, spent dialysis fluid may be drained through the connection intothe empty bag.

BRIEF DESCRIPTION OF THE DRAWINGS

A written description setting forth the best mode presently known forcarrying out the present invention, and of the manner of implementingand using it, is provided by the following detailed description ofillustrative embodiments, which refers to the accompanying drawingswherein:

FIG. 1 is a schematic diagram of a patient having a peritoneum accesstube to which a bag of fresh dialysis fluid is being connected;

FIG. 2 illustrates irradiation with ultraviolet light of the connectionof the bag and tube to have an antimicrobial effect on the same;

FIG. 3 illustrates the infusion of fresh dialysis fluid from the baginto the patient;

FIG. 4 illustrates the disconnecting of the empty bag after infusion;

FIG. 5 illustrates the capping of the access tube after disconnection ofthe empty bag;

FIG. 6 illustrates irradiation of the connection between the bag andaccess tube after reconnection;

FIG. 7 illustrates the draining of spent dialysis fluid from thepatient's peritoneal cavity;

FIG. 8 illustrates the disconnection of the bag from the access tubefollowing drainage;

FIG. 9 illustrates the first step in repeating the procedure outlined byFIGS. 1-3;

FIG. 10 is a schematic diagram of an alternate structure for theperitoneum access tube;

FIG. 11 is a schematic diagram of an alternate structure for carryingout CAPD using a branched tubing segment having both a bag of freshdialysis fluid and an empty bag for receiving spent dialysis fluid;

FIG. 12 illustrates irradiation with ultraviolet light of the connectionbetween the access tube extension and the branched tubing segment;

FIG. 13 illustrates the infusion of fresh dialysis fluid into thepatient;

FIG. 14 illustrates the step of disconnecting the bags and tubingsegments from the access tube;

FIG. 15 is a cross-sectional side view of an embodiment of the UV lightbox shown in FIG. 2;

FIG. 16 is a cross-sectional end view of the light box shown in FIG. 15;

FIG. 17 is a schematic diagram of circuitry for controlling theoperation of the UV lamps in the light box of FIGS. 15 and 16 based upona prescribed elapsed exposure time; and

FIG. 18 is a schematic diagram of circuitry for controlling theoperation of the UV lamps in the light box of FIGS. 15 and 16 based upona predetermined amount of radiation exposure.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to the drawings, a patient 10 undergoing continuous ambulatoryperitoneal dialysis (CAPD) has a fluid flow path established to hisperitoneal cavity. Suitably, the fluid flow path is established by acatheter system comprising a surgically-implanted indwelling catheter 11having mated to it a connecting tube 12 which terminates at a matingconnector 14. The peritoneal catheter 11 may be, for example, aTenckhoff catheter. Tube 12 is connected to catheter 11 by means ofconnector 15 integral with catheter 11 mating with connector 17 which isintegral with one end of tube 12. Since the connection formed byconnector 15 mating with connector 17 does not relate specifically toapplicants' invention, for purposes of clarity it is not shown in FIGS.2-9; the presence of the connection and catheter 11 in FIGS. 2-9 should,however, be inferred. Additionally, for simplicity in referencing thefluid flow path establishing means comprising the catheter 11, tube 12and connectors 14, 15 and 17, the terminology "peritoneum access tube"will occasionally be used in the description which follows.

As indicated by FIG. 1, a method of peritoneal dialysis therapy inaccordance with the present invention proceeds with a source of freshdialysis fluid being connected to the peritoneum access tube. As shownin FIG. 1, the source of fresh dialysis fluid may suitably be a bag 16having an outlet tube 18 which terminates at a connector 20. Connector20 is adapted for mating connection with connector 14 of the peritoneumaccess tube. Connectors 14 and 20 are suitably a Luer-lock typeconnector. Bag 16 suitably has a volume capacity of about 2 liters foradults. Alternatively, the source of fresh dialysis fluid may be anotherform of container, such as a glass bottle. Also, the source of freshdialysis fluid could be a fluid dispensing or cycling machine.

As shown in FIG. 1, outlet tube 18 and tube 12 are both closed bypinch-type clamps. Specifically, clamp 22 provides a means of openingand closing outlet tube 18, and clamp 24 provides a means of opening andclosing tube 12 to fluid flow. With clamps 22 and 24 closing theirrespective tube, the connectors 14 and 20 at the end of their respectivetube and that portion of the tube between the connectors and the clampsis susceptible to bacterial contamination; this portion will be referredto as a "potential contamination zone", and is indicated in FIG. 1 bythe crosshatching.

Referring next to FIG. 2, after connecting bag 16 to the peritoneumaccess tube, by engaging connector 14 with connector 20, at least thepotential contamination zone is exposed to ultraviolet radiation to havean antimicrobial effect on the zone. Suitably, the potentialcontamination zone is exposed to ultraviolet radiation by irradiationwith ultraviolet light in the wavelength range of 2400-2800 Angstroms,which is a known antimicrobial wavelength range of UV. The light shouldbe of sufficient intensity to penetrate the connectors and tubingsegments, so as to reach all internal surfaces which may come intocontact with dialysis fluid being infused into the patient.

The required total antimicrobial ultraviolet radiation exposure is, ofcourse, dependent upon the type and number of microorganisms to bekilled. As an example, consider Asporgillus niger in a concentration of3.6×10⁵ spores/ml. To achieve a 99% kill, a total UV radiation exposuredosage of up to 527,540 μWs/cm² would be required.

The total UV radiation exposure dosage is a product of the intensity ofthe radiation and the time of exposure. Accordingly, by dividing thedosage by exposure time, the required UV intensity can be calculated.Because incident radiation intensity is affected by the focussinggeometry between the UV source and the potential contamination zone, andby the UV transmittance of the materials used for the tubes andconnectors, the transmittance impedances of these items must be takeninto consideration in determining the required lamp output intensity. Itis reasonable to expect that a 50% loss in lamp output intensity willresult in most cases.

Finally, UV intensity is a function of total output power from the UVsource and the surface area being irradiated. Thus, to determine lampoutput power, the surface area to be irradiated must be calculated.

Assuming a length of tubing 11.5 inches long and 1/4 inch in diameter tobe irradiated, the surface area is 58.27 cm². To produce a dosage of527,540 μWs/cm² with a 60 seconds exposure time, the intensity requiredwould be 8,792 μW/cm². If there is a 50% power loss, the required lampoutput intensity would be 17,584 μW/cm². Thus, the lamp output powerwould have to be about 1 watt.

Irradiation of the potential contamination zone may be accomplished byplacing the portion of tubes 12 and 18 between clamps 22, 24, as well asclamps 22 and 24 themselves, in a UV light box 26 having a UV lamp 28.Suitably, lamp 28 may be a mercury vapor lamp.

Connectors 14 and 20, tubes 12 and 18 and clamps 22, 24 must be made ofa material which is transmissive to ultraviolet radiation in the2400-2800 Angstroms wavelength range. Suitable materials includepolycarbonate, polyvinylidene fluoride, FEP-Teflon®, andpolyvinylchloride.

As indicated in FIG. 3, after irradiation of the potential contaminationzone, clamps 22 and 24 are released so that dialysis fluid may beinfused from bag 16 through the peritoneum access tube into thepatient's peritoneal cavity.

It will, of course, be understood that although FIG. 3 indicates thatinfusion takes place after removal of the connection and tubing fromlight box 26, ultraviolet irradiation may continue during dialysis fluidinfusion if so desired.

After infusion of fresh dialysis fluid, tube 12 is clamped off at clamp24. Bag 16 and the interconnected tubes 12 and 18 may be rolled-up andcarried by the patient under his clothes. Alternatively, as indicated inFIG. 4, the empty bag 16 may be disconnected from the peritoneum accesstube by disconnecting connector 20 from connector 14. If such adisconnection is made, then preferrably, as indicated in FIG. 5, a cap30 is placed on connector 14.

After the desired period of residency within the peritoneal cavity, thedialysis fluid must be drained. If the bag which carried fresh dialysisfluid has been rolled-up and carried by the patient, then drain ofdialysis fluid is readily accomplished by unrolling the bag andunclamping the peritoneum access tube and bag outlet tube at clamps 24and 22, respectively. Then, after draining the fluid, tube 12 is againclamped at clamp 24, and the bag is disconnected from the peritoneumaccess tube. The steps shown in FIGS. 1-3 are then repeated to refillthe peritoneal cavity with fresh dialysis fluid.

If the emptied bag has been disconnected and the peritoneum access tubecapped, a slightly different procedure is followed. First, theperitoneum access tube is uncapped and an empty bag is connected to theperitoneum access tube. Then, the potential contamination zone betweenclamps 22 and 24 is exposed to ultraviolet radiation to have anantimicrobial effect on the fluid flow path therethrough. As shown inFIG. 7, after irradiation of the potential contamination zone, clamps22, 24 are released and spent dialysis fluid is drained from thepatient's peritoneal cavity into bag 16. It is preferred that thepotential contamination zone be irradiated prior to drain because of thepotential retrograde movement of bacteria along tube 12 into theperitoneum, which potential increases if irradiation occurs for thefirst time simultaneous with the beginning of drain. In FIG. 7, theconnected tubes 12 and 18 are shown as remaining in light box 26 whilespent dialysis fluid is being drained. This is suitable. However, it isalso suitable to remove the connected tubes from the light box duringdrain of the spent dialysis fluid.

After the fluid has been drained, tubes 12 and 18 are clamped and thenow filled bag is disconnected from the peritoneum access tube, asindicated in FIG. 8. Then, as indicated in FIG. 9, a new bag 32 of freshdialysis fluid is connected to the peritoneum access tube. FIG. 9corresponds to FIG. 1 and represents the initial step in repeating thedescribed method.

FIGS. 10-14 illustrate an alternative apparatus which can be used topractice the method of this invention. As shown in FIG. 10, a tubingsegment 40 has connectors 42, 44 at opposite ends of tubing segment 40.A clamp 46 is provided on tubing segment 40. Connector 42 on tubesegment 40 connects to connector 15 on catheter 11, while connector 44on the opposite end of tubing segment 40 carries a cap 48. In carryingout the procedure shown in FIGS. 11-13, cap 48 of FIG. 10 would beremoved and connector 52 on tube segment 50 would be connected toconnector 44.

Referring further to FIG. 11, there is illustrated an alternateapparatus for carrying out continuous ambulatory peritoneal dialysis onpatient 10. In place of the single bag structure shown in FIG. 1, thealternate structure illustrated in FIG. 11 comprises a tube segment 50having connectors 52, 54 at opposite ends and a clamp 56 intermediatethe ends. A branched tubing segment 58, having connector 60 affixed tothe end, connects with tubing segment 50 by means of engagement ofconnector 60 with connector 54. Branched tubing segment 58 includes basetubing segment 62 which branches into branch tubing segments 64 and 66.Branch tubing segment 64 connects to a first container 68, which may bea flexible, collapsable bag filled with fresh dialysis fluid. Branchtubing segment 66 connects to a second container, which may also be aflexible, collapsable bag, but which is empty and adapted to receivespent dialysis fluid drained from the patient. Bags 68 and 70 may bepermanently affixed to branch tubing segments 64, 66; or alternatively,each bag 68, 70 may be removably connected to respective branch tubingsegments 64, 66 by a connector.

To carry out continuous ambulatory peritoneal dialysis using theapparatus illustrated in FIG. 11, connector 52 is first connected toconnector 44. Since connectors 44 and 52 are open, as are portions oftubing segments 40 and 50, up to the respective clamps 46, 56, there ispotential contamination of that portion which is crosshatched in FIG.11. Accordingly, after connection of tubing segments 40 and 50, thepotential contamination zone is placed in UV light box 26 and exposed toultraviolet light; this step is illustrated in FIG. 12.

As represented by FIG. 13, after irradiation of the potentialcontamination zone, clamps 46 and 56 are opened, opening tube segments40 and 50 to enable dialysis fluid flow from bag 68 after opening clamp67. In this manner, infusion of fresh dialysis fluid into the patienttakes place. If desired, irradiation of tubing segments 40 and 50 maycontinue during dialysis fluid infusion.

In the situation where the patient's peritoneal cavity is filled withdialysis fluid (which will be the typical situation regardless ofwhether the FIG. 1 or FIG. 11 apparatus is used), the cavity would, ofcourse, first be drained, with the fluid going into bag 70 after clamp69 is opened. Preferably, prior to drain, irradiation with UV occurs,and the irradiation may be continued during drain and the subsequentinfusion from bag 68. It is recognized that regardless of whether apatient uses the apparatus of FIG. 1 or the apparatus of FIG. 11, somepatients may desire to minimize the time required to complete the methodof this invention. It may be possible to eliminate the necessity ofirradiating prior to drain if adequate antimicrobial effect can beobtained and retrograde contamination prevented in the case whereirradiation first begins simultaneous with the beginning of drain; thusno time would be added to the exchange procedure by irradiation.

In FIG. 14, there is illustrated the step of disconnecting tubingsegments 50, 62, and bags 68, 70 from the access tube. This, of course,is accomplished by disconnecting connectors 44 and 52, after whichconnector 44 is covered with cap 48 ("capping off").

The tubing segments 50, 62 and bags 68, 70 may then be discarded.

The apparatus of FIG. 1 and Fig. 11 are distinguishable, and havecomparative advantages and disadvantages. A patient selecting either theFIG. 1 or the FIG. 11 apparatus should be aware of the trade-offs. Forexample, although the FIG. 1 apparatus is simpler in design than FIG.11, use of the FIG. 1 apparatus, with the patient also "capping off",will require two UV irradiations to complete the entire drain, infusionand dwell cycle; incidentially, this is the order in which drain,infusion, and dwell will most commonly occur when the entire patientpopulation is considered.

FIG. 2 shows one irradiation which is required using FIG. 1 apparatus:irradiation prior to infusion. FIG. 6 shows the second irradiation whichis necessary if the patient "caps off": irradiation prior to drain.

Typically in an exchange procedure, irradiation prior to drain willoccur before irradiation to infusion. There are a limited number ofsituations, however, in which a patient will infuse prior to drain,e.g., a new CAPD patient who has no dialysis solution in his peritonealcavity. One of the prime advantages of CAPD is the nearly continuouspresence of dialysis fluid in the peritoneal cavity providing a gentlecontinuous dialysis contributing to stable blood chemistries and theconsequent general feeling of well-being experienced by CAPD patients.

The FIG. 11 apparatus has the potential advantage of requiring only oneirradiation if the patient "caps off": irradiation prior to drain. Thisadvantage is realized because of the branch tubing segmented design ofFIG. 11 which leads to both drain and infusion bags. But most probablythe FIG. 11 apparatus will be more expensive to manufacture than theFIG. 1 apparatus, and potentially a patient may find the FIG. 11apparatus cumbersome to handle.

Referring to FIG. 15, there is shown in a cross-sectional side viewapparatus for implementing the light box 26 shown in FIGS. 1-14. Lightbox 26 includes a base portion 72 having a bottom 74, front and backwalls (not shown), and end walls 76, 80. Light box 26 also includes ahinged lid 82 adapted to be placed upon base portion 72. Lid 82comprises a top 84, front and back walls (not shown), and end walls 86,88. Light box 26 also has a shelf 90 disposed in base portion 72, shelf90 extending horizontally between end walls 76, 80 and the front andback walls.

Openings 92 and 94 are provided in the end walls of the light box.Suitably, the openings are formed at the seam where the bottom edge ofthe lid end walls meet the top edge of the base portion end walls.Openings 92 and 94 are adapted to permit passage therethrough of tubingsegments. For example, referring to FIG. 2, tubing segments 12 and 18would pass through openings 94 and 92, respectively, with lid 82 closed.Disposed around opening 92 on the outside of box 26 is a light shieldand tubing guide 96. Similarly, around opening 94 is a light shield andtubing guide 98. Internally of light box 26 and attached to the top sideof shelf 90, are tubing clips 100 and 102. The clips stand vertically,and are provided to hold and properly position a connection junction andadjacent portions of access tube 12 and tube 18 along a prescribed axis.It is to be noted, however, that clips 100 and 102 do not correspond toclamps 22, 24 in FIG. 2.

Also contained internally of light box 26 are ultraviolet lamps.Suitably, four UV lamps are utilized. In FIG. 15, only lamps 104 and 106are in view. Lamp 104 and another behind it, but not in view, aremounted in lid 84. Lamp 106 and another behind it, but not in view, aremounted in base portion 72.

Preferably, the interior surfaces of lid 82 and base portion 72 arecovered with a layer of ultraviolet light reflective material. Forexample, polished aluminum could be used.

Referring to FIG. 16, there is presented a cross-sectional end view oflight box 26. As shown therein, lid 82 is connected to base portion 72by hinge connection 83. Also in view in FIG. 16 are UV lamps 108 and110. The four UV lamps are symmetrically arranged around an axis definedby tubing clips 100, 102. Reflector shields 115, 117, 119 and 121 arealso provided to direct lamp output radiation toward the axis defined byclips 100, 102.

Referring again to FIG. 15, beneath shelf 90 in base portion 72 is theelectrical power and control circuitry for the UV lamps. Suitably,electrical power for the UV lamps is provided by an ac plug-in cord 112and an internal power supply. Also included are lamp ballasts 114, 116,which are mounted to the bottom panel of base portion 72. Circuitry forcontrolling electrical power to the UV lamps is packaged and mounted tothe under side of shelf 90.

Referring now to FIG. 17, there is presented one suitable implementationof electronic circuitry for controlling the UV lamps. The circuitryshown provides both on-off control and elapsed time control. Beforediscussing the specifics of the circuitry in FIG. 17, first to bedescribed is the provision of microswitch 105 (see FIG. 16) to detectwhether the lid is opened or closed, and microswitches 107, 109 (seeFIG. 15) to detect whether tubing segments are properly positioned inthe support clips. Microswitch 105 can be a contact microswitch whichmay be readily utilized in a conventional manner, as is well-known tothose skilled in the field of electronics, to generate logic signalsindicative of the open/closed status of the switch. For purposes ofexplanation in connection with FIG. 17, it is assumed that themicroswitch 105 for detecting lid closure generates a high or logic "1"signal when the lid is closed. Also, it is assumed that themicroswitches 107, 109 on the tubing segment support clips generate ahigh or logic "1" signal when the tubing segments are properly placed toreceive UV radiation.

Continuing with reference to FIG. 17, the signals from the lid andsupport clip microswitches are applied to AND-gate 130. If a logic "1"is present on all three inputs to gate 130, a signal is produced whichplaces electronic switch 132 in a conducting state and applies positivevoltage to node 134. If, however, any one of the microswitch signals isa logic "0", switch 132 remains in the non-conducting state meaningthere is a clip misalignment or lid closure problem. If desired, anindicator, for example a light emitting diode, can be connected to eachof the gate 130 inputs to indicate the status of each microswitchsignal, and thereby provide a visual means to enable the patient todetermine if there is a clip misalignment or lid closure problem.

An irradiation cycle start switch 136 is connected to node 134.Connected in series with switch 136 is an RC network comprising resistor138 and capacitor 140. The gate of SCR 142 is connected via conductor144 to the connection node 146 of the components of the RC network. Theanode of the SCR 142 is connected to node 134. The cathode of SCR 142 isapplied to the voltage input of a timer circuit 148.

Closure of switch 136 applies electrical energy from the power source,for example, a dc power supply, to the RC network. Current flow throughresistor 138 charges capacitor 140 to a voltage level sufficient to"gate-on" SCR 142. A conduction path is established through SCR 142between the power supply and timer circuit 148. Energization of circuit148 initiates its activity. Simultaneously, electrical power is appliedto an indicator in the form of a light emitting diode 150 having aseries-connected, currentlimiting resistor 152.

The RC network of resistors 138, 139 and capacitor 140 provides a shortdelay of a few milliseconds. The delay is optional and need not beincluded, in which case the gate of SCR 142 is connected directly toswitch 136.

Timer circuit 148 may suitably comprise a NE555 integrated circuitdevice utilized in a monostable mode of operation. The timing period ofthe device's operation is established by an RC network comprisingresistor 154 and capacitor 156. The RC network comprising resistors 158,160, 162 and capacitor 164, which network is connected to the triggerinput of device 148, provides the trigger input signal to initiateoperation of the timer circuit. When triggered, timer circuit 148changes its output state on line 166 and in effect "latches" into an"on" state.

The output signal available over line 166 from timer circuit 148 isapplied to a transistor driver 168 which has coil 170 of a relayconnected to the collector. Relay coil 170 controls relay contacts 172,which in turn controls the application of electrical power to the UVlamps.

The timer circuit is "on" for a period of time defined by the values ofresistor 154 and capacitor 156, thus enabling control of the time the UVlights are on. This time period is, of course, selectable and serves asan elapsed time counter for an irradiation cycle.

Referring now to FIG. 18, there is shown a schematic diagram ofcircuitry for controlling the electrical power to the UV lamps basedupon measurement of the cumulative ultraviolet light exposure duringeach cycle. Exposure control may be utilized along with or as asubstitute for elapsed time lamp control. Control of electrical power tothe UV lamps based upon cumulative ultraviolet light exposure wouldcompensate for lamp degradation over time.

Referring to FIG. 18, a UV light sensor 180 receives light from the UVlamps in the light box. For simplicity, the diagrammed lamp is labeledwith reference numeral 182. The output signal generated by detector 180is applied to an amplification block 184 which provides signal gain. Theoutput of amplifier 184 is applied to a readout meter 186 whichindicates the intensity level of the UV lamp 182. The output ofamplifier 184 is also applied to the non-inverting input of a comparator186. Also connected to the non-inverting input of comparator 186 is ashunt capacitor 188. The inverting input of comparator 186 is connectedto the wiper of potentiometer 190, which sets the threshold level forthe comparator.

The output signal from amplifier 184 charges capacitor 188. When avoltage is established on capacitor 188 which exceeds the referencelevel set by potentiometer 190, comparator 186 "switches" and produces apositive-going voltage transition on line 192. It will, of course, beappreciated that the rate at which capacitor 188 charges will bedirectly proportional to the intensity of light from lamp 182. Thus, asthe lamp intensity decreases, the time required to charge capacitor 188will increase.

The output of comparator 186 is used to clock flip-flop 194. At thebeginning of an irradiation cycle, as initiated by closure of switch136, one-shot 196 is triggered and produces a reset pulse to flip-flop194. Resetting of flip-flop 194 establishes the Q output at a logic "0",which after inversion by inverter 198 applies a logic "1" to OR-gate200. The output of OR-gate 200 provides turn-on drive to transistor 168(also shown in FIG. 17). The second input to OR-gate 200 is line 166from timer circuit 148 in FIG. 17.

When there has been sufficient ultraviolet light exposure of a potentialcontamination zone, for example, as shown in FIG. 2, capacitor 188 willhave charged to the voltage necessary to effect switching of comparator186. The output voltage transition from comparator 186 clocks flip-flop194 setting the Q output to a logic "1". Inversion of this signal byinverter 198 produces a logic "0" which is ineffective to cause OR-gate200 to turn on transistor 168. The logic "1" condition of the Q outputof flip-flop 194 is also applied via resistor 202 to transistor 204. Thecollector of transistor 204 is connected through resistor 206 tocapacitor 188. The logic "1" condition on the Q output causes transistor204 to turn on and discharge capacitor 188 to condition it for the nextirradiation cycle.

It will be appreciated that although timer circuit 148 in FIG. 17 may"time-out" indicating that the desired elapsed time has expired, if thecumulative ultraviolet light exposure has not reached a certain minimumlevel, as established by the reference voltage on the inverting input ofcomparator 186, OR-gate 200 will continue to apply turn-on drive totransistor 168 until the cumulative exposure level has been attained andflip-flop 194 is clocked.

The foregoing description has been of particular implementations of thepresent invention for purposes of explanation and illustration. It willbe apparent to those skilled in this art that many modifications andchanges in the implementations shown may be made without departing fromthe basic teachings of the present invention. Accordingly, that subjectmatter, and all equivalents thereof, which Applicants regard to be theirinvention is set forth in the following claims.

What is claimed is:
 1. A method of peritoneal dialysis therapy of apatient having a peritoneum access tube extending through the abdominalwall, for establishing a fluid flow path to the peritoneal cavity,comprising the steps of:connecting a container of fresh dialysis fluidto said peritoneum access tube; irradiating the connection junctionbetween the container and the access tube with a sufficient quantity ofultraviolet radiation so that an antimicrobial effect is obtained atsaid connection junction; and infusing the fresh dialysis fluid into thepatient.
 2. The method of claim 1 wherein said irradiating step iscontinued during the infusion of the dialysis fluid.
 3. The method ofclaim 1 further comprising the steps of:allowing the dialysis fluid toremain within the patient's peritoneal cavity for a residence timeperiod; draining the dialysis fluid from the patient's peritoneal cavityafter the residence time period; and disconnecting said container fromsaid access tube.
 4. A method of peritoneal dialysis therapy of apatient having an indwelling catheter implanted in his peritoneal cavityand extending through his abdomen, said catheter interconnected with anaccess tube, comprising the steps of:connecting an empty container tothe access tube; irradiating a potential contamination zone between theindwelling catheter and said empty container, including at least aportion of the access tube, with a sufficient quantity of ultravioletradiation so that an antimicrobial effect is obtained in said potentialcontamination zone; draining dialysis fluid from the patient'speritoneal cavity and into the empty container through the access tube;disconnecting the now-filled said empty container; connecting a sourceof fresh dialysis fluid to the peritoneum access tube; and infusing saiddialysis fluid into the patient's peritoneal cavity through the accesstube.
 5. A method of peritoneal dialysis therapy of a patient,comprising the steps of:establishing a fluid flow path to the peritonealcavity of the patient; connecting a container of fresh dialysis fluid tosaid fluid flow path; irradiating the connection junction between thecontainer and the fluid flow path with a sufficient quantity ofultraviolet radiation so that an antimicrobial effect is obtained onsaid connection junction; infusing said dialysis fluid into thepatient's peritoneal cavity through the fluid flow path; allowing thedialysis fluid to remain within the patient's peritoneal cavity for aresidence time period; and draining the dialysis fluid from thepatient's peritoneal cavity after the residence time period.
 6. A methodof performing peritoneal dialysis on a patient by adding freshperitoneal dialysis solution to the peritoneal cavity of a patient in amanner that decreases the likelihood of transmitting microbialcontamination to the peritoneal cavity of the patient, the methodcomprising the steps of:connecting a first container filled with freshperitoneal dialysis solution, and a second container which is empty, toa conduit in flow communication with the patient's peritoneal cavity;exposing at least the connection junction between the conduit and thecontainers to a sufficient quantity of ultraviolet radiation so that anantimicrobial effect is obtained at said connection junction; flowingfresh peritoneal dialysis solution from the first container into thepatient's peritoneal cavity via said conduit; and therafter drainingspent peritoneal dialysis solution from the patient's peritoneal cavityvia said conduit into said empty container.
 7. Apparatus forinterconnection with a catheter and access tube communicating with theperitoneal cavity of a patient for conducting continuous ambulatoryperitoneal dialysis, which comprises:a tubing segment including abranched tubing portion having a first and second branches whichrespectively communicate with a first container filled with peritonealdialysis solution and a second empty container; an aseptic connector atone end of said tubing segment for connection to the catheter accesstube; a clamp for controlling flow through said tubing segment andisolating said branched tubing portion from the connector to create anaseptic barrier when the connector is disconnected; and an ultravioletlight applicator means for irradiating at least the portion of thetubing segment between the connector and the clamp.